v3.26.3
Shareholder Report, Line Graph (Details) - USD ($)
 12 Months Ended 24 Months Ended 36 Months Ended 48 Months Ended 60 Months Ended 72 Months Ended 84 Months Ended 96 Months Ended 108 Months Ended 120 Months Ended
Aug. 31, 2016
Aug. 31, 2026
Aug. 31, 2017
Aug. 31, 2018
Aug. 31, 2019
Aug. 31, 2020
Aug. 31, 2021
Aug. 31, 2022
Aug. 31, 2023
Aug. 31, 2024
Aug. 31, 2025
Aug. 31, 2026
C000074146 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Nomura Tax-Free USA Fund (Institutional Class) – including sales charge                    
Accumulated Value $ 10,000   $ 10,058 $ 10,220 $ 11,109 $ 11,520 $ 12,606 $ 11,033 $ 10,986 $ 12,327 $ 11,720 $ 12,427
C000006387 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Nomura Tax-Free USA Fund (Class C) – including sales charge                    
Accumulated Value 10,000   9,958 10,026 10,783 11,071 11,987 10,392 10,240 11,382 10,717 11,252
C000006385 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Nomura Tax-Free USA Fund (Class A) – including sales charge                    
Accumulated Value 9,550   9,577 9,715 10,528 10,891 11,883 10,379 10,305 11,541 10,938 11,570
C000006388 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Nomura Tax-Free USA Intermediate Fund (Class A) – including sales charge                    
Accumulated Value 9,725.06   9,751.55 9,807.03 10,564.66 10,857.43 11,493.22 10,306.31 10,323.63 11,268.19 10,994.81 11,463.07
C000006390 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Nomura Tax-Free USA Intermediate Fund (Class C) – including sales charge                    
Accumulated Value 9,999.99   9,944.33 9,916.18 10,592.58 10,793.3 11,326.99 10,076.68 10,017.76 10,853.42 10,510.5 10,876.46
C000074147 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Nomura Tax-Free USA Intermediate Fund (Institutional Class) – including sales charge                    
Accumulated Value 10,000   10,036.11 10,110.69 10,912.56 11,232 11,904.45 10,693.81 10,741.78 11,748.46 11,498.69 12,018.13
Bloomberg Municipal Bond Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Bloomberg Municipal Bond Index                    
Accumulated Value 10,000   10,088 10,138 11,022 11,378 11,765 10,749 10,932 11,598 11,607 12,085
Bloomberg 3 15 Year Blend Municipal Bond Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Bloomberg 3–15 Year Blend Municipal Bond Index                    
Accumulated Value $ 10,000   $ 10,109 $ 10,114 $ 10,939 $ 11,310 $ 11,621 $ 10,797 $ 10,978 $ 11,555 $ 11,766 $ 12,111